Customerio Core Feature

---
name: customerio-core-feature
description: 'Implement Customer.io core features: transactional messages,

  API-triggered broadcasts, segments, and person merge.

  Trigger: "customer.io segments", "customer.io transactional",

  "customer.io broadcast", "customer.io merge users", "customer.io send email".

  '
allowed-tools: Read, Write, Edit, Bash(npm:*), Bash(npx:*), Glob, Grep
version: 1.14.0
license: MIT
author: Jeremy Longshore <jeremy@intentsolutions.io>
tags:
- saas
- customer-io
- transactional
- broadcasts
- segments
compatibility: Designed for Claude Code
---
# Customer.io Core Features

## Output

- A scoped, consent-aware Customer.io feature configuration with a validated data contract and owner.
- A test receipt showing intended audience, environment, event/message behavior, and safe rollback path.

## Examples

Configure a feature in development with a synthetic profile and a narrowly defined event. Verify attributes, segment membership, and message preview before promotion. If the audience or consent behavior differs from expectation, disable the development configuration and correct the contract before proceeding.

## Overview

Implement Customer.io's key platform features: transactional emails/push (password resets, receipts), API-triggered broadcasts (one-to-many on demand), segment-driving attributes, anonymous-to-known user merging, and person suppression/deletion.

## Prerequisites

- `customerio-node` installed
- Track API credentials (`CUSTOMERIO_SITE_ID` + `CUSTOMERIO_TRACK_API_KEY`)
- App API credential (`CUSTOMERIO_APP_API_KEY`) — required for transactional + broadcasts

## Instructions

### Feature 1: Transactional Email

Transactional messages are opt-in-implied messages (receipts, password resets). Create the template in Customer.io dashboard first, then call the API with data.

```typescript
// lib/customerio-transactional.ts
import { APIClient, SendEmailRequest, RegionUS } from "customerio-node";

const api = new APIClient(process.env.CUSTOMERIO_APP_API_KEY!, {
  region: RegionUS,
});

// Send a transactional email
// transactional_message_id comes from the Customer.io dashboard template
async function sendPasswordReset(email: string, userId: string, resetUrl: string) {
  const request = new SendEmailRequest({
    to: email,
    transactional_message_id: "3",  // Template ID from dashboard
    message_data: {
      reset_url: resetUrl,
      expiry_hours: 24,
      support_email: "help@yourapp.com",
    },
    identifiers: { id: userId },    // Links delivery metrics to user profile
  });

  const response = await api.sendEmail(request);
  // response = { delivery_id: "abc123", queued_at: 1704067200 }
  return response;
}

// Send an order confirmation with complex data
async function sendOrderConfirmation(
  email: string,
  userId: string,
  order: { id: string; items: { name: string; qty: number; price: number }[]; total: number }
) {
  const request = new SendEmailRequest({
    to: email,
    transactional_message_id: "5",
    message_data: {
      order_id: order.id,
      items: order.items,        // Accessible as {{ event.items }} in Liquid
      total: order.total,
      order_date: new Date().toISOString(),
    },
    identifiers: { id: userId },
  });

  return api.sendEmail(request);
}
```

**Dashboard setup:** Create transactional message at Transactional > Create Message. Use Liquid syntax: `{{ data.reset_url }}`, `{{ data.order_id }}`, `{% for item in data.items %}`.

### Feature 2: Transactional Push

```typescript
import { APIClient, SendPushRequest, RegionUS } from "customerio-node";

const api = new APIClient(process.env.CUSTOMERIO_APP_API_KEY!, {
  region: RegionUS,
});

async function sendPushNotification(userId: string, title: string, body: string) {
  const request = new SendPushRequest({
    transactional_message_id: "7",  // Push template ID
    identifiers: { id: userId },
    message_data: { title, body },
  });

  return api.sendPush(request);
}
```

### Feature 3: API-Triggered Broadcasts

Broadcasts send to a pre-defined segment on demand. Define the segment and message in the dashboard, then trigger via API.

```typescript
// lib/customerio-broadcasts.ts
import { APIClient, RegionUS } from "customerio-node";

const api = new APIClient(process.env.CUSTOMERIO_APP_API_KEY!, {
  region: RegionUS,
});

// Trigger a broadcast to a pre-defined segment
async function triggerProductUpdateBroadcast(version: string, changelog: string) {
  await api.triggerBroadcast(
    42,                           // Broadcast ID from dashboard
    { version, changelog },       // Data merged into Liquid template
    { segment: { id: 15 } }      // Target segment (defined in dashboard)
  );
}

// Trigger broadcast to specific emails
async function triggerBroadcastToEmails(
  broadcastId: number,
  emails: string[],
  data: Record<string, any>
) {
  await api.triggerBroadcast(
    broadcastId,
    data,
    {
      emails,
      email_ignore_missing: true,  // Don't error on unknown emails
      email_add_duplicates: false,  // Skip if user already in broadcast
    }
  );
}

// Trigger broadcast to specific user IDs
async function triggerBroadcastToUsers(
  broadcastId: number,
  userIds: string[],
  data: Record<string, any>
) {
  await api.triggerBroadcast(broadcastId, data, { ids: userIds });
}
```

### Feature 4: Segment-Driving Attributes

Segments in Customer.io are data-driven — they automatically include/exclude people based on attributes you set via `identify()`.

```typescript
// services/customerio-segments.ts
import { TrackClient, RegionUS } from "customerio-node";

const cio = new TrackClient(
  process.env.CUSTOMERIO_SITE_ID!,
  process.env.CUSTOMERIO_TRACK_API_KEY!,
  { region: RegionUS }
);

// Update attributes that drive segment membership
async function updateEngagementAttributes(userId: string, metrics: {
  lastActiveAt: Date;
  sessionCount: number;
  totalRevenue: number;
  daysSinceLastLogin: number;
}) {
  await cio.identify(userId, {
    last_active_at: Math.floor(metrics.lastActiveAt.getTime() / 1000),
    session_count: metrics.sessionCount,
    total_revenue: metrics.totalRevenue,
    days_since_last_login: metrics.daysSinceLastLogin,
    engagement_tier: metrics.sessionCount > 50 ? "power_user"
      : metrics.sessionCount > 10 ? "active"
      : "casual",
  });
}

// Segment examples built in dashboard:
// "Power Users": engagement_tier = "power_user"
// "At Risk": days_since_last_login > 30 AND plan != "free"
// "High Value": total_revenue > 500
// "Trial Expiring": plan = "trial" AND trial_end_at < now + 3 days
```

### Feature 5: Merge Duplicate People

```typescript
// Merge a secondary (duplicate) person into a primary person.
// The secondary is deleted permanently after merge.
async function mergeUsers(
  primaryId: string,
  secondaryId: string,
  identifierType: "id" | "email" | "cio_id" = "id"
) {
  await cio.mergeCustomers(
    identifierType,
    primaryId,
    identifierType,
    secondaryId
  );
  // Secondary person is permanently deleted.
  // Their attributes and activity merge into the primary.
}
```

### Feature 6: Suppress and Delete People

```typescript
// Suppress: user stays in system but receives no messages
async function suppressUser(userId: string): Promise<void> {
  await cio.suppress(userId);
}

// Delete: remove user entirely from Customer.io
async function deleteUser(userId: string): Promise<void> {
  await cio.destroy(userId);
}
```

## Error Handling

| Error | Cause | Solution |
|-------|-------|----------|
| `422` on transactional | Wrong `transactional_message_id` | Verify template ID in Customer.io dashboard |
| Missing Liquid variable | `message_data` incomplete | Ensure all `{{ data.x }}` variables are in `message_data` |
| Broadcast `404` | Invalid broadcast ID | Check broadcast ID in dashboard Broadcasts section |
| Segment not updating | Attribute type mismatch | Dashboard segments compare types strictly — number vs string matters |
| Merge fails | Secondary person doesn't exist | Verify both people exist before merging |

## Resources

- [Transactional API](https://docs.customer.io/journeys/transactional-api/)
- [Transactional Examples](https://docs.customer.io/journeys/transactional-api-examples/)
- [API-Triggered Broadcasts](https://docs.customer.io/journeys/api-triggered-broadcasts/)
- [Manual Segments](https://docs.customer.io/journeys/manual-segments/)

## Next Steps

After implementing core features, proceed to `customerio-common-errors` for troubleshooting.